Two hours before cooking, take the prime rib out of the refrigerator to allow to come completely to room temperature. Rub all of the exposed surfaces with the sea salt.
When you are ready to start cooking, preheat the oven to 200 degrees F. Place the meat bone side down on a rack in a roasting dish. Cook for 4-6 hours, or until an internal thermometer reads 125 degrees (for medium-rare; 135 for medium), keeping in mind that the roast will rise in temperature 5 degrees as it cools.
Let the roast cool for 30-45 minutes while you increase the oven temperature to 500 degrees. Place the roast back in the oven for 7-10 minutes to let the skin get crispy. Watch it carefully here, as it can burn easily! Once you take it out of the oven it only needs a few minutes to cool; the meat on the inside has already rested.
Notes
Alternately, you can brown the outside of the meat for 7-10 minutes in a skillet once the meat has rested.
Recipe by Autoimmune Wellness at https://autoimmunewellness.com/slow-roasted-prime-rib/